Silverstripe UserForms provides a visual form builder for the Silverstripe CMS. From 6.0.0 until 6.4.9, 7.0.7, and 7.1.1, the userform email recipient subject field in the CMS accepts a specially crafted payload that can be interpreted as executable server-side code. An authenticated CMS user with permission to configure a UserForms email recipient can use the subject field to run arbitrary code on the server, compromising confidentiality, integrity, and availability. This issue is fixed in versions 6.4.9, 7.0.7, and 7.1.1.
CVE-2026-54721
HIGHPre-NVD 8.88.8—
EchelonGraph scoreMEDIUM confidence
This high-severity CVE scores 8.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 66% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, secondary
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.8Exploit: None knownExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 8.8
- EG Score
- 8.8(medium)
- EG Risk
- 40(Track)EG Risk 40/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity88% × 45%Exploitation0% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 34%
- KEV
- Not listed
Published
August 27, 2026
Last Modified
August 28, 2026
Advisory Details (8)
Auto-updated Aug 27, 2026Patch available. Sources: github_commit, github_pr, github_release, github.
github Patch Available
Remote code execution via userforms email subject · Advisory · silverstripe/silverstripe-userforms · GitHub
https://github.com/silverstripe/silverstripe-userforms/security/advisories/GHSA-g8wr-r2v2-vqc6github_release Patch Available
7.1.1
Patch available: silverstripe/silverstripe-userforms 7.1.1
https://github.com/silverstripe/silverstripe-userforms/releases/tag/7.1.1github_release Patch Available
7.0.7
Patch available: silverstripe/silverstripe-userforms 7.0.7
https://github.com/silverstripe/silverstripe-userforms/releases/tag/7.0.7github_release Patch Available
6.4.9
Patch available: silverstripe/silverstripe-userforms 6.4.9
https://github.com/silverstripe/silverstripe-userforms/releases/tag/6.4.9github_pr Patch Available
[CVE-2026-54721] Prevent RCE via email recipient subject
Patch available: silverstripe/silverstripe-userforms 6.4.9 (PR #1442 merged 2026-06-24)
https://github.com/silverstripe/silverstripe-userforms/pull/1442github_pr Patch Available
[CVE-2026-54721] Prevent RCE via email recipient subject
Patch available: silverstripe/silverstripe-userforms 7.0.7 (PR #1441 merged 2026-06-24)
https://github.com/silverstripe/silverstripe-userforms/pull/1441github_commit Patch Available
commit c55494ad7c71 (silverstripe/silverstripe-userforms)
Patch available: silverstripe/silverstripe-userforms 6.4.9 (contains commit c55494ad7c71)
https://github.com/silverstripe/silverstripe-userforms/commit/c55494ad7c717b199a3c1663b43a54db5d95604cgithub_commit Patch Available
commit 23c069866900 (silverstripe/silverstripe-userforms)
Patch available: silverstripe/silverstripe-userforms 7.0.7 (contains commit 23c069866900)
https://github.com/silverstripe/silverstripe-userforms/commit/23c069866900c19b499bfa997d1e251e97491702Vendor Advisories for CVE-2026-54721(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(1 across 1 ecosystem)
Packagist(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| silverstripe/userforms | 0.5.1 ... v5.9.2 (172 versions) | 6.4.9 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 7× in last 7d / 7× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-08-30 01:22 UTCEPSS rescore
- 2026-08-29 08:57 UTCEG score recompute
- 2026-08-28 21:41 UTCEPSS rescore
- 2026-08-28 20:43 UTCEG score recompute
- 2026-08-28 19:47 UTCEG score recompute
- 2026-08-27 20:27 UTCEG score recompute
- 2026-08-27 17:23 UTCEG score recompute
Related CVEs(same CWE)
Same CWE
10 shownCWE-94
- CVE-2003-1432EG 10.0EPSS p94HIGH
- CVE-2002-0495EG 10.0EPSS p96HIGH
- CVE-1999-0702EG 10.0EPSS p98HIGH
- CVE-1999-0509EG 10.0EPSS p98HIGH
- CVE-2006-1318EG 9.3EPSS p97HIGH
- CVE-2006-1301EG 9.3EPSS p95HIGH
- CVE-2006-1308EG 9.3EPSS p95HIGH
- CVE-2006-1309EG 9.3EPSS p95HIGH
- CVE-2006-1304EG 9.3EPSS p96HIGH
- CVE-2006-1306EG 9.3EPSS p95HIGH
Frequently asked(5)
What is CVE-2026-54721?
CVE-2026-54721 is a high vulnerability published on August 27, 2026. Silverstripe UserForms provides a visual form builder for the Silverstripe CMS. From 6.0.0 until 6.4.9, 7.0.7, and 7.1.1, the userform email recipient subject field in the CMS accepts a specially crafted payload that can be interpreted as executable server-side code. An authenticated CMS user with…
When was CVE-2026-54721 disclosed?
CVE-2026-54721 was first published in the National Vulnerability Database on August 27, 2026, with the most recent update on August 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-54721 actively exploited?
CVE-2026-54721 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 65.5% of all scored CVEs.
What is the CVSS score of CVE-2026-54721?
CVE-2026-54721 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2026-54721?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-54721, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-54721
Is Your Infrastructure Affected by CVE-2026-54721?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.